Coltart, Don M.2019-11-07August 2012019-08August 201Portions of this document appear in: Alfie, Rachel J., Ngoc Truong, Julianne M. Yost, and Don M. Coltart. "A kinetically controlled direct aldol addition of α-chloro thioesters via soft enolization." Tetrahedron letters 58, no. 3 (2017): 185-189. And in: Truong, Ngoc, Scott J. Sauer, Cyndie Seraphin-Hatcher, and Don M. Coltart. "Direct carbon–carbon bond formation via reductive soft enolization: a syn-selective Mannich addition of α-iodo thioesters." Organic & biomolecular chemistry 14, no. 33 (2016): 7864-7868. And in: Rastelli, Ettore J., Ngoc T. Truong, and Don M. Coltart. "Asymmetric induction in hydroacylation by cooperative iminium ion–transition-metal Catalysis." Organic letters 18, no. 21 (2016): 5588-5591.https://hdl.handle.net/10657/5311The research presented in this dissertation is consisted of three synthetic endeavors. In the first, the constructions of α-halo-β-hydroxy- and α-halo-β-amino thioesters, which are useful synthetic intermediates, are prepared by the aldol or Mannich addition of α-halo enolates to aldehydes and imines, respectively. The transformations are achieved via soft enolization approach. The method offers a mild and operationally simple procedure that circumvents the need for prior enolate formation which involves harsh conditions. The “direct” process, in which a weak base and a Lewis acid works in a concerted manner to effect deprotonation, allows enolization of a carbonyl compound without affecting the coupling partner. Taken to the advantage of soft enolization and a kinetically-controlled condition, diastereoselectivity can be achieved toward the synthesis of α-chloro-β-hydroxy- and α-iodo-β-amino thioesters. The second endeavor pertains to a new strategy in rhodium catalyzed enantioselective hydroacylation reaction. This is achieved intramolecularly through the merger of transition-metal catalysis and the iminium-ion catalysis that delivers enantioenriched cyclopentanones. Asymmetric induction is derived from a readily accessible, inexpensive chiral nonracemic secondary amine rather than chiral nonracemic phosphines that is typically employed in the conventional enantioselective hydroacylation reactions. Finally, the third project focuses on the utilization of the 1,3-dipolar nature of 3-amino-1-N-phenyl azopropenes toward a cascading cycloaddition fashion to the in situ generated benzynes. The newly formed C(sp3)-N bond allows for the formation of saturated N-heterocycles which received considerable attention due to their solitary chemical, biological and pharmacological importance.application/pdfengThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).Soft enolizationAlpha-Chloro-beta-Hydroxy ThioestersAlpha-Iodo-beta-Amino Thioesters Enantioselective HydroacylationsTransition-Metal and Iminium Ion CatalysisAsymmetric Induction1,3-Dipolar Cycloaddition3-Amino-1-N-Phenyl Azopropenes2019-11-07Thesisborn digital